The invention relates to a device for dispensing a mixture of pasty substance and at least one additive, in particular in the form of a striped ribbon. The device is of the type including a container and a dispenser head that is provided with a closure means and is fixed on the container by fixation means cooperating with means for keeping them connected to the container. The head includes a central channel, open at two ends and closed by a side wall, that discharges into an outlet conduit from the head, and the side wall includes at least one auxiliary channel. The dispenser head comprises a removable cap, which includes a reservoir that contains the additive and communicates with the outlet conduit from the cap via at least one of the channels.